Pulse-electrodeposited nickel phosphide for high-performance proton exchange membrane water electrolysis

Abstract Ni-P catalysts with various compositions were fabricated by pulse electrodeposition in pursuit of highly efficient and durable hydrogen evolution via proton exchange membrane water electrolysis. Pulse electrodeposition enabled the preparation of a Ni-P catalyst with a high portion of P, thereby conferring acid-resistant properties to the catalyst. Specifically, precise control of the deposition potential made it possible to leach Ni from bulk Ni-P and thus to vary the composition. With greater P incorporation, the catalyst became amorphous. The activity of the as-prepared Ni-P catalysts for the hydrogen evolution reaction (HER) in acidic medium was evaluated by cyclic voltammetry, confirming the strong dependence of the activity on the composition. The Ni-P catalyst with a bulk composition of Ni78P22 exhibited the best HER activity with an overpotential of 105 mV at −10 mA cm−2. The current density of the single cell with the electrodeposited Ni78P22 cathode and electrodeposited IrO2 anode was 1.31 A cm−2 at 2.0 Vcell. Compared to reported values for other non-Pt or Pt cathodes for electrolysis, the electrolyzer with the Ni78P22 cathode strongly outperforms the non-Pt cathodes, and the performance is more than a half of that of the Pt cathode.